The French Socialist Party (Parti socialiste français) was founded in 1902. It came from the merger of the "possibilist

Possibilism (French Socialist)

The Possibilists was a trend in the French socialist movement led by Paul Brousse, Benoît Malon and others who brought about a split in the French Workers' Party in 1882...

" Federation of the Socialist Workers of France

Federation of the Socialist Workers of France

France's first socialist party, the Federation of the Socialist Workers of France , was founded in 1879. It was characterised as "possibilist" because it promoted gradual reforms.-Formation:...

 (FTSF), Jean Allemane

Jean Allemane

Jean Allemane was a French socialist politician, veteran of the Paris Commune of 1871, pioneer of syndicalism, leader of the Socialist-Revolutionary Workers' Party and co-founder of the unified French Section of the Workers' International in 1905...

's Revolutionary Socialist Workers' Party (POSR) and some independent socialist politicians like Jean Jaurès

Jean Jaurès

Jean Léon Jaurès was a French Socialist leader. Initially an Opportunist Republican, he evolved into one of the first social democrats, becoming the leader, in 1902, of the French Socialist Party, which opposed Jules Guesde's revolutionary Socialist Party of France. Both parties merged in 1905 in...

. Jaurès became the party leader.

Unlike the Socialist Party of France

Socialist Party of France (1902)

The Socialist Party of France was founded in 1902, during a congress in Commentry, by the merger of the Marxist French Workers' Party led by Jules Guesde and the Blanquist Central Revolutionary Committee of Édouard Vaillant....

 led by Jules Guesde

Jules Guesde

Jules Basile Guesde was a French socialist journalist and politician.Guesde was the inspiration for a famous quotation by Karl Marx. Shortly before Marx died in 1883, he wrote a letter to Guesde and Paul Lafargue, both of whom already claimed to represent "Marxist" principles...

, it supported the principle of the alliance with the non-Socialist left in the Bloc des gauches

Bloc des gauches

 The Bloc des gauches , aka Bloc républicain was a coalition of Republican political forces created during the French Third Republic in 1899 to contest the 1902 legislative elections...

. Finally, in 1905, under pressure from the Second International

Second International

The Second International , the original Socialist International, was an organization of socialist and labour parties formed in Paris on July 14, 1889. At the Paris meeting delegations from 20 countries participated...

, the two parties merged into the French Section of the Workers' International.